This invention relates to a thermally imagable business record, such as a form, label, tag, or the like, in which a selected area may be activated to form a thermal image. More particularly, the invention relates to a substrate containing a thermally imagable coating on at least one selected area of its surface while the remaining areas of the substrate are left uncoated.
In the field of product labeling, direct thermal printing has been a well-known means of non-impact printing. Direct thermal printers are capable of forming images by the application of heat to a substrate containing heat-reactive chemicals thereon. Typically, a substrate such as paper is coated with a coating of color forming and color developing reactants, which, when heated, combine to form a visible image. When such a coated substrate passes under the print head of a thermal printer, the areas containing the coating are activated by the heated print elements, forming images on the surface of the substrate.
Thermally imagable coatings provide a convenient method of providing computer generated data such as bar codes or serial numbers. Such information may be printed on business forms such as labels or tags. Thermally coated substrates have also been widely used as facsimile paper, bar code paper for point-of-sale (POS) systems, automatic ticket vending machines, and labels for food products. There are various compositions and methods of applying thermally sensitive coatings as described, for example, in U.S. Pat. Nos. 4,865,939, 4,861,749, and 4,894,359.
However, while the use of thermally imagable coatings is a convenient method of providing a printable surface, the present method of applying the coatings is to cover the surface of the substrate completely. This method is both expensive and wasteful as the thermally imagable coating is applied to areas of the substrate which are not subsequently imaged.
Further, as the application of thermally sensitive coatings requires sophisticated coating equipment and techniques, it has heretofore been impractical to apply the coatings only in selected areas or to apply the coatings at the same time a business record is manufactured. Additionally, as thermally imagable coatings are typically applied to a high volume of substrates which are widely distributed for different end uses, manufacturers have produced fully coated webs or sheets to accommodate the greatest number of end uses of the products.
Accordingly, there is still a need in the art for a thermally imagable business record, such as a form, label or the like, in which a thermally imagable coating may be applied in a cost effective manner to a selected area or areas of the form so that information is printed through the use of a thermal printer only at desired locations.